The downside is that they regard others to be used, don't feel sympathy, empathy or guilt, and are often one step away from becoming what psychologists used to call psychopaths: criminally vindictive types whose only motivation is to take advantage of weaker people.

In her book, Thomas describes many disturbing episodes from her own life, including the time she let a baby possum drown in her swimming pool because she couldn't be bothered to fish it out with the net. In another chapter, she describes a recurring dream in which she kills her father with her bare hands — because she hates him.

Thomas is also a successful law professor, has children, and teaches Sunday school. Or so she says — grandiose lying is one of the characteristics of being a sociopath.

Psychologists have changed the diagnostic definition of sociopathy several times over the decades. It used to be called being a "psychopath." Sociopath is the newer term. More recently, the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition has renamed the condition "Antisocial Personality Disorder" and reduced it to seven main characteristics.

However, the first researcher to name the concept of psychopathy was Dr. Hervey Cleckley, who published a book titled "The Mask of Sanity" in 1941, Thomas writes.

Cleckley noted that psychopathy was difficult to diagnose precisely because it presents itself without the obvious symptoms of mental disorder. Psychopaths and sociopaths are often a bit too rational.

In her new book, Thomas says Cleckley's 16 behavioral characteristics hit home. "Nowhere else have I recognized the sociopath inside me more than in Cleckley's clinical profiles," she writes.

Here are Cleckley's 16 characteristics. Ask yourself if they apply to you.